R/V Roger Revelle Expedition KNOX03RR
CLIVAR/CO2 cruise I8S
Chief Scientist Weekly Report 6, 12 March 2007

1600 local; 30.6 °S, 95.0 °E; air temp 20 °C (69 °F), wind 10 knots from Northwest

We have now completed 83 stations on our “I8S CLIVAR/CO2 transect”. “Best News of the Week” is, hands down, that we finally shook loose from the grip of the Southern Ocean, which held its teeth in us a good long while. Not that our science operations were all that impeded. Winds and swell stayed up, but within operational limits - at least for the main rosette program. By calling for very slow line payout for the first hour or more of a deep cast we were able to keep CTD cable tension swings manageable, at the cost of extra time spent on each station. But the strain was telling. And trace metal rosette casts, which are carried out over the stern, were just not possible for a few days. What a relief when we finally worked our way into the subtropics: gentle seas, warm weather, sunshine … ah, it was Easy Street to us! We’re a happy bunch, with end of the cruise in sight. What wonderful conditions in which to complete our work.

It was the transmissometer’s turn to be problem child of the week. This device is mounted on the rosette and feeds a signal into the CTD related to the clarity of the water, a signal in turn related to the amount of particulate matter suspended in the seawater, another facet of the carbon system. Odd behavior from both the primary and back-up instruments was finally tracked to a coincidence of faults in two cables, not the instruments. We’re back on line now with those measurements.

Our graduate students deserve a turn in the spotlight. We have along JJ Becker, Dian Putrasahan, and Lora Van Uffelen of SIO, and David Ullman from the University of Wisconsin. In every respect they are valued members of our team, each with a niche in our operations. They work hard, ask great questions, put up with sea stories from the senior scientists, and they come up with surprises, too. For example, one evening JJ popped up a Google Earth image of the "antipodes" of our cruise track. What is an antipode? For a point on the Earth, the antipode is the opposite point on the Earth’s sphere (where a line drawn from the point through the Earth’s center would come out). Well, it turns out the antipodes of our cruise track lie in areas of the Earth where most of us can readily judge scale. We'd show you JJ’s image, but it is too large a file for a weekly report. Jules Hummon kindly made us a line-drawing version, which we have attached to this report. You will see that if we'd done the “antipode cruise”, we would have begun off Spain, steamed into the far north regions of Canada (blue line), carried out our stations (red line) through North America to just off the Florida panhandle, then steamed at cruise end to a spot near Bermuda. Puts a great perspective on the Revelle's actual Southern Hemisphere track (left panel), doesn't it?

We have time for only a few more stations before heading to Fremantle. We’ll send a final cruise report the end of the week. Data quality remains mind bogglingly good. Morale, teamwork, food, weather - all great! All is very well, indeed.

Jim Swift and Annie Wong
chief and co-chief scientists, CLIVAR/I8S

I8S antipodes